Field of the Invention
The present invention relates to fire-retardant compositions and, in particular, to improved ammonium polyphosphate based fire-retardant compositions.
Description of the Related Art
It is known to use ammonium polyphosphate based fire-retardant compositions to combat wildland fires. However, ammonium polyphosphate is corrosive and may damage equipment used to produce, store, handle and apply the fire-retardant composition. There is accordingly a need for corrosion inhibiting agents which reduce the corrosivity of ammonium polyphosphate based fire-retardant compositions. Ammonium polyphosphate based fire-retardant compositions may also include a thickening agent, a coloring agent and a suspending agent that carries the coloring agent.
U.S. Pat. No. 6,802,994 which issued on Sep. 12, 2004 to Kegeler et al., and the full disclosure of which is incorporated herein by reference, discloses corrosion inhibited fire-retardant compositions. The corrosion inhibited fire retardant compositions are comprised of an ammonium polyphosphate, a suspending agent, and a corrosion inhibiting system. The corrosion inhibiting system is comprised of at least one corrosion inhibiting agent selected from a group of corrosion inhibiting agents including azoles, insoluble ferric pyrophosphate, soluble ferric pyrophosphate, ferrous oxalate, ferric citrate, ferrous sulfate, ferric ammonium citrate, insoluble ferric orthophosphate, soluble ferric orthophosphate, ferric ammonium oxalate, ferric ammonium sulfate, ferric bromide, ferric sodium oxalate, ferric stearate, ferric sulfate, ferrous acetate, ferrous ammonium sulfate, ferrous bromide, ferrous gluconate, ferrous iodide, ferric acetate, ferric fluoroborate, ferric hydroxide, ferric oleate, ferrous fumarate, ferrous oxide, ferric lactate, ferric resinate and any combination thereof. The corrosion inhibiting system is typically present in the fire retardant composition of the invention in a minor amount effective to substantially reduce corrosiveness of the concentrated fire retardant composition and of its diluted solution.
U.S. Pat. No. 6,905,639 which issued on Jun. 14, 2005 to Vandersall et al., and the full disclosure of which is incorporated herein by reference, discloses corrosion-inhibited fire-retardant compositions. The corrosion-inhibited fire-retardant compositions are comprised of an ammonium polyphosphate, at least one biopolymer having a particle size diameter of less than about 100 microns, and a corrosion inhibiting system. The corrosion inhibiting system is comprised of at least one corrosion inhibiting agent selected from a group of corrosion inhibiting agents including azoles, insoluble ferric pyrophosphate, soluble ferric pyrophosphate, ferrous oxalate, ferric citrate, ferrous sulfate, ferric ammonium citrate, soluble ferric orthophosphate, insoluble ferric orthophosphate, ferric ammonium oxalate, ferric ammonium sulfate, ferric bromide, ferric sodium oxalate, ferric stearate, ferric sulfate, ferrous acetate, ferrous ammonium sulfate, ferrous bromide, ferrous gluconate, ferrous iodide, ferric acetate, ferric fluoroborate, ferric hydroxide, ferric oleate, ferrous fumarate, ferrous oxide, ferric lactate, ferric resinate and any combination thereof. In a specific embodiment, the corrosion-inhibited fire retardant composition includes a xanthan biopolymer.
U.S. Pat. No. 8,202,449 which issued on Jun. 19, 2012 to Garner et al., and the full disclosure of which is incorporated herein by reference, discloses a fire-retardant composition comprising an ammonium polyphosphate, a suspending agent and a corrosion inhibiting agent. When in solution the corrosion inhibiting agent includes at least one ion selected from the group of ions consisting of aluminum ions, ferric ions, calcium ions and magnesium ions. Said ions complex an effective amount of fluoride ions present in the fire-retardant composition to reduce the corrosiveness of the fire-retardant composition.